glapi_getproc.c File Reference

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Detailed Description

Code for implementing glXGetProcAddress(), etc.

This was originally in glapi.c but refactored out.

#include <stdlib.h>
#include <string.h>
#include "main/glheader.h"
#include "main/compiler.h"
#include "glapi.h"
#include "glapioffsets.h"
#include "glapitable.h"
#include "glprocs.h"

Data Structures
struct	_glapi_function
	Track information about a function added to the GL API. More...
Defines
#define	NEED_FUNCTION_POINTER
Functions
static void	fill_in_entrypoint_offset (_glapi_proc entrypoint, GLuint offset)
	This function inserts a new dispatch offset into the assembly language stub that was generated with the preceeding function.
static char *	str_dup (const char *str)
	strdup() is actually not a standard ANSI C or POSIX routine.
static const glprocs_table_t *	find_entry (const char *n)
	Search the table of static entrypoint functions for the named function and return the corresponding glprocs_table_t entry.
static GLint	get_static_proc_offset (const char *funcName)
	Return dispatch table offset of the named static (built-in) function.
static _glapi_proc	get_static_proc_address (const char *funcName)
	Return dispatch function address for the named static (built-in) function.
static const char *	get_static_proc_name (GLuint offset)
	Return the name of the function at the given offset in the dispatch table.
static _glapi_proc	generate_entrypoint (GLuint functionOffset)
	Generate a dispatch function (entrypoint) which jumps through the given slot number (offset) in the current dispatch table.
static struct _glapi_function *	add_function_name (const char *funcName)
	Generate new entrypoint.
PUBLIC int	_glapi_add_dispatch (const char *const *function_names, const char *parameter_signature)
	Fill-in the dispatch stub for the named function.
PUBLIC GLint	_glapi_get_proc_offset (const char *funcName)
	Return offset of entrypoint for named function within dispatch table.
_glapi_proc	_glapi_get_proc_address (const char *funcName)
	Return pointer to the named function.
const char *	_glapi_get_proc_name (GLuint offset)
	Return the name of the function at the given dispatch offset.
Variables
static struct _glapi_function	ExtEntryTable [MAX_EXTENSION_FUNCS]
static GLuint	NumExtEntryPoints = 0

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Define Documentation

#define NEED_FUNCTION_POINTER

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Function Documentation

PUBLIC int _glapi_add_dispatch	(	const char *const *	function_names,
		const char *	parameter_signature
	)

Fill-in the dispatch stub for the named function.

This function is intended to be called by a hardware driver. When called, a dispatch stub may be created created for the function. A pointer to this dispatch function will be returned by glXGetProcAddress.

Parameters:

	function_names	Array of pointers to function names that should share a common dispatch offset.
	parameter_signature	String representing the types of the parameters passed to the named function. Parameter types are converted to characters using the following rules: 'i' for GLint, GLuint, and GLenum 'p' for any pointer type 'f' for GLfloat and GLclampf 'd' for GLdouble and GLclampd

Returns:

The offset in the dispatch table of the named function. A pointer to the driver's implementation of the named function should be stored at dispatch_table[offset]. Return -1 if error/problem.

See also:

glXGetProcAddress

Warning:

This function can only handle up to 8 names at a time. As far as I know, the maximum number of names ever associated with an existing GL function is 4 (glPointParameterfSGIS, glPointParameterfEXT, glPointParameterfARB, and glPointParameterf), so this should not be too painful of a limitation.

Todo:

Determine whether or not parameter_signature should be allowed to be NULL. It doesn't seem like much of a hardship for drivers to have to pass in an empty string.

Todo:

Determine if code should be added to reject function names that start with 'glX'.

Bug:

Add code to compare parameter_signature with the parameter signature of a static function. In order to do that, we need to find a way to get the parameter signature of a static function.

_glapi_proc _glapi_get_proc_address

(

const char *

funcName

)

Return pointer to the named function.

If the function name isn't found in the name of static functions, try generating a new API entrypoint on the fly with assembly language.

const char* _glapi_get_proc_name

(

GLuint

offset

)

Return the name of the function at the given dispatch offset.

This is only intended for debugging.

PUBLIC GLint _glapi_get_proc_offset

(

const char *

funcName

)

Return offset of entrypoint for named function within dispatch table.

static struct _glapi_function* add_function_name

(

const char *

funcName

)

[static, read]

Generate new entrypoint.

Use a temporary dispatch offset of ~0 (i.e. -1). Later, when the driver calls _glapi_add_dispatch we'll put in the proper offset. If that never happens, and the user calls this function, he'll segfault. That's what you get when you try calling a GL function that doesn't really exist.

Parameters:

funcName

Name of the function to create an entry-point for.

See also:

_glapi_add_entrypoint

static void fill_in_entrypoint_offset	(	_glapi_proc	entrypoint,
		GLuint	offset
	)			[static]

This function inserts a new dispatch offset into the assembly language stub that was generated with the preceeding function.

static const glprocs_table_t* find_entry

(

const char *

n

)

[static]

Search the table of static entrypoint functions for the named function and return the corresponding glprocs_table_t entry.

static _glapi_proc generate_entrypoint

(

GLuint

functionOffset

)

[static]

Generate a dispatch function (entrypoint) which jumps through the given slot number (offset) in the current dispatch table.

We need assembly language in order to accomplish this.

static _glapi_proc get_static_proc_address

(

const char *

funcName

)

[static]

Return dispatch function address for the named static (built-in) function.

Return NULL if function not found.

static const char* get_static_proc_name

(

GLuint

offset

)

[static]

Return the name of the function at the given offset in the dispatch table.

For debugging only.

static GLint get_static_proc_offset

(

const char *

funcName

)

[static]

Return dispatch table offset of the named static (built-in) function.

Return -1 if function not found.

static char* str_dup

(

const char *

str

)

[static]

strdup() is actually not a standard ANSI C or POSIX routine.

Irix will not define it if ANSI mode is in effect.

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Variable Documentation

struct _glapi_function ExtEntryTable[MAX_EXTENSION_FUNCS] [static]

GLuint NumExtEntryPoints = 0 [static]

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